In an existing system, when there is data to transmit on the Iub port (an interface between the Serving Node B and the Service Radio Net Controller (hereinafter referred to as SRNC)) and the Iur port (an interface between SRNC and control RNC), in every transmission time interval, the data frame is transmitted from SRNC to Serving Node B for the downlink transmission, and the data frame is transmitted from Serving Node B to SRNC for the uplink transmission. The Enhanced Dedicated Transport Channel (hereinafter referred to as E-DCH) data frame is a type of data frame, which is used in the uplink direction and comprised by higher-layer signal indication. The E-DCH data frame is defined with two types of structure: Type 1 and Type 2. If Medium Access Control-enhanced sublayer Protocol Data Unit (hereinafter referred to as MAC-es PDU) is comprised, Type 1 structure is used; and if Medium Access control-improved sublayer Protocol Data Unit (hereinafter referred to as MAC-is PDU) is comprised, Type 2 structure is used.
FIG. 1A and FIG. 1B show the structures of the E-DCH data frame Type 1 and Type 2 respectively. As shown in FIG. 1A and FIG. 1B, both Type 1 and Type 2 comprise two parts: header and payload. The difference is the data unit type comprised. Each E-DCH comprises the following several fields.
1. Header Cyclic Redundancy Check (Hereinafter Referred to as CRC) Field
The “CRC check code” field is the result of the CRC applied to the remaining part of the header (i.e. from bit 0 of the first byte to bit 0 (comprised) of the last byte of the header (not comprising the Header CRC Cont four bits)) with the corresponding generator polynomials. The length of the “header CRC check code” field adapted to an E-DCH uplink data frame is 7 bits or 11 bits. The 7 bits are bit 7 to bit 1 of the first byte of the frame header of the E-DCH data frame, and the 11 bits further contain bits from bit 7 to bit 4 of the second byte besides of the bits from bit 7 to bit 1 of the first byte.
2. Frame Type Indicator
The “frame type indicator” field is used to indicate whether a frame is a data frame or a control frame. The length of the “frame type indicator” field is one bit and it is located in bit 0 of the first byte of the frame header in the E-DCH data frame. The E-DCH data frame is an uplink data frame, and therefore, as described above, its “frame type indicator” field is “0”.
3. Frame Sequence Number (Hereinafter Referred to as FSN)
The “frame sequence number” field represents the FSN of an E-DCH data frame, and for each transmitted E-DCH data frame, it has to generate its own FSN. If the FSN is 4 bits, then it is calculated according to the following formula:FSN=(FSN+1) modulo 16.
The range of the FSN value is 0-15. The length of the “frame sequence number” field is 4 bits and it is located from bit 3 to bit 0 of the second byte of the frame header of the E-DCH data frame.
4. Number of Subframes
The “number of subframes” field indicates how many subframes are in a frame. Please note that a subframe comprises a header portion and a payload portion. The value range of the “number of subframes” field is 1-16, in which, the binary code of value 1 is “0000”, and the binary code of value 16 is “1111”. The length of the “number of subframes” field is 4 bits, and it is located from bit 3 to bit 0 of the third byte of the frame header of the E-DCH data frame.
5. Connection Frame Number
For E-DCH, the “connection frame number” field indicates a radio frame that the HARQ decodes data accurately. For E-DCH, this field is adapted to the purpose of re-ordering, and CFN (and subframe number) can be adapted to dynamic delay measurements. The value range is 0-255. The length of the “connection frame number” field is 8 bits and it is located from bit 7 to bit 0 of the fourth byte of the frame header of the E-DCH data frame.
6. Number of HARQ Retransmissions
The “number of HARQ retransmissions” field indicates the number of HARQ retransmissions for successfully decoding the payload, or as to the HARQ decoding failure situation, this field indicates the number of HARQ retransmissions that were used at the time when the HARQ decoding failure is detected. And the value of this field being 13 indicates that the actual retransmitted data is inappropriate to be used as the input of the outer loop power control. The value of this field being 15 indicates that the node B is incapable of calculating the number of HARQ retransmissions. The value range is 0-15. The length of the “number of HARQ retransmissions” field is 4 bits and it is located from bit 3 to bit 0 of the fifth byte of the frame header of the E-DCH data frame; the “number of HARQ retransmissions” field of the first subframe number is located from bit 6 to bit 3 of the fifth byte of the frame header of the E-DCH data frame; the “number of HARQ retransmissions” field of the second subframe number is located from bit 6 to bit 3 of the first byte of the frame header of the E-DCH data frame after the first MAC-e header. The location of the “number of HARQ retransmissions” fields of other subframe numbers in the frame header of the E-DCH data frame can be deduced in the same manner, till this subframe comprises the number of HARQ retransmissions of all the MAC-es PDUs.
7. Subframe Number
The “subframe number” field indicates the subframe number in which the payload is received. Except for the purpose of re-ordering, the subframe number (and control frame number) may be used as dynamic delay measurement. The value range of the “subframe number” field is 0-4 and the length is 3 bits; the first subframe number is located from the bit 2 to the bit 0 of the fifth byte of the frame header of the E-DCH data frame; the second subframe number is located from the bit 2 to the bit 0 of the first byte after the first MAC-e or MAC-i header of the frame header of the E-DCH data frame; and other subframe numbers are located from the bit 2 to the bit 0 of the first byte after the previous MAC-e or MAC-i header of the frame header of the E-DCH data frame, till all the subframe numbers are comprised.
8. Spare Extension
The “spare extension” field indicates the location where new Information Elements (IEs) can in the future be added in a backward compatible way. The length of this field is 0-32 bytes.
9. Payload CRC
The “payload CRC” field is the CRC check of the payload. It is the result of the CRC applied to the remaining portion of the payload, that is, from the bit 7 of the first byte of the payload to the bit 0 of the payload before the payload CRC. The length is 16 bits.
If the decoding of the E-DCH payload is successful, the E-DCH data frame is written in the above mentioned format, and sent by Serving Node B to SRNC.
If the decoding of the E-DCH payload is unsuccessful and one of the following conditions is satisfied, Serving Node B will send a HARQ failure indication to SRNC (Non-serving Node B will not send a HARQ failure indication).
Condition 1: a MAC-e or MAC-i protocol data unit for a HARQ process has not yet been successfully decoded and the Retransmission Sequence Number (hereinafter referred to as RSN) indicates a new MAC-e or MAC-i protocol data unit transmitted for the same HARQ process, and the HARQ retransmission number that had already occurred was equal or higher than the lowest of the maximum HARQ retransmissions values for the terminal's configured MAC-d flows.
Condition 2: a MAC-e or MAC-i for a HARQ process has not yet been successfully decoded, and the maximum retransmissions for the MAC-d flow with the highest maximum HARQ retransmissions value valid for the terminal connection have occurred, or should have occurred in case the HARQ related outband signaling (for example RSN) on the E-DPCCH could not be decoded.
Condition 3: an MAC-e or MAC-i for an HARQ process has not yet been successfully decoded when MAC-e or MAC-i Reset is performed in the terminal. The Node B knows the timing of the MAC-e or MAC-i Reset in the terminal via higher layer.
The HARQ failure indication is only sent at one transmission bearer. Serving Node B may select any transmission bearer associated with the terminal related to this HARQ failure indication.
If the HARQ failure is indicated in the user data frame, it is called HARQ failure indication data frame. As shown in FIG. 2A and FIG. 2B, the detailed configuration of it is as follows.
1. When a failure is detected, the connection frame number and the subframe number Information Elements values will reflect this time.
2. Type 1: as shown in FIG. 2A, the number of MAC-es protocol data units is set to 0. As a consequence, there are no Information Elements of DDI and N in the header. In order to have the octet aligned structure, 4 bits padding is used after number of MAC-es protocol data unit Information Element, and there are no MAC-es protocol data units Information Elements in the payload part of the data frame related to HARQ failure.
3. Type 2: as shown in FIG. 2B, the number of MAC-is protocol data units is set to 0. As a consequence, there are no Information Elements of MAC-is protocol data descriptor in the header. There are no MAC-is protocol data units Information Elements in the payload part of the data frame related to HARQ failure.
4. The Number of HARQ retransmissions Information Element is set to be the Number of HARQ retransmissions occurred when the failure was detected. The coding method is the same as for a correctly decoded payload described above.
SRNC decodes the Number of HARQ retransmissions from the received correctly-decoded E-DCH data fame header as the input of Outer Loop Power Control, or decodes the Number of HARQ retransmissions from the E-DCH data fame header of HARQ failure indication as the input of Outer Loop Power Control. If the Signal Interference Ratio (hereinafter referred to as SIR) of Outer Loop Power Control is modified, SRNC comprises new SIR target in the Outer Loop Power Control frame and sends it to Serving Node B. The Inner Loop Power Control function located at Serving Node B will use the new SIR target to perform power emission of the control terminal, and therefore minimize interference and maintain quality of connection.
Now, Dual-carrier technology is gradually introduced into the existing system. In the system which adopts Dual-carrier technology, if the above mentioned HARQ failure indication is used, the following problems may occur:
Serving Node B may receive MAC-es PDUs or MAC-is PDUs sent from two carriers from the air interface, and the decoding of data on both carriers may fail at the same time, or one succeeds and the other fails; while the HARQ failure indication in the existing system only regards the decoding failure of MAC-es PDUs or MAC-is PDUs on one carrier, without indicating the carrier property of HARQ failure indication. If one of the MAC-e PDU or MAC-i PDU received by Serving Node B from two carriers from the air interface fails, or both fail, then enter one HARQ failure indication data frame, that is, the decoding failure of MAC-es PDUs or MAC-is PDUs on two carriers share one HARQ failure indication data frame. However, Outer Loop Power Control (hereinafter referred to as OLPC) is calculated based on the HARQ retransmission data of E-DCH protocol data frame header or the HARQ retransmission data of HARQ failure indication frame header. Using current HARQ failure indication data frame can not inform which carrier the Number of HARQ retransmissions belong to, so SRNC can not know the retransmission times of the data flow on each carrier, and therefore can not perform OLPC.